package VacationHomework.LeetCode;

public class Num21 {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
    if(l1==null){
        return l2;
    }
    if(l2==null){
        return l1;
    }
    ListNode newHead=new ListNode(-1);
    ListNode cur=newHead;
    while (l1!=null && l2!=null){
        if(l1.val<=l2.val){
            cur.next=l1;
            cur=l1;
            l1=l1.next;
        }else {
            cur.next=l2;
            cur=l2;
            l2=l2.next;
        }
    }
    if(l1!=null){
        cur.next=l1;
    }
    if(l2!=null){
        cur.next=l2;
    }
    return newHead.next;
    }
}
